Goosefoot starfish
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Goosefoot starfish ( Anseropoda placenta ) |
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| Anseropoda placenta | ||||||||||||
| ( Pennant , 1777) |
The goosefoot starfish ( Anseropoda placenta ) is a starfish from the family Asterinidae in the order of the valve stars (Valvatida), which is native to the coasts of the Northeast Atlantic and the Mediterranean . It mainly feeds on crabs .
features
Anseropoda placenta has approximately the shape of a very flat pentagon with five short blunt arms, between the tips of which the edge is clearly concave, and reaches a diameter of up to 20 cm. The skin of the starfish is grainy. This comes about through small groups of fine, umbrella-like platelets (paxilles), which are arranged in the middle and along the radial center lines running from here to the arm tips. The paxilles on the underside of the starfish are slightly larger. Pedicellariums are absent, and skin gills (papules) are only found in the center and along the radial midlines. The upper surface is red or pink in the middle and along the radial center lines, the reticulated skin in between pale pink or white. The underside is yellow with a red stripe around the edges. The suction feet on the underside are in two rows.
Reproduction
Females and males of Anseropoda placenta come together in summer to release their germ cells into the open water. The rather large eggs are fertilized in the open water and develop via a free-swimming bipinnaria larva, which later metamorphoses into a starfish in the brachiolaria stage .
Distribution and occurrence
Anseropoda placenta is distributed on the coasts of the eastern North Atlantic from the Shetland Islands to the south, around the British Isles and France, and in the Mediterranean . Here it is found on sandy subsoil below the intertidal zone at depths of around 10 m to 200 m, sometimes up to 600 m.
The copepod Asterocheres siphonatus is often associated with Anseropoda placenta .
nutrition
Anseropoda placenta feeds mainly on crabs - amphipods , cumaceae , hover shrimp and decapods such as hermit crabs - but also mussels and echinoderms .
According to observations by Guillou (1987) feeding young animals, especially small crabs and go with increasing size over on small shells, while adult goose foot starfish small decapods (especially porcelain crabs of the genus Porcellana ) and brittle stars of the genus Ophiothrix prefer. The prey is therefore selected primarily on the basis of size.
The food spectrum is thus partly similar to that of the related New Zealand species Stegnaster inflatus , but unlike this, the trapping mechanism in Anseropoda placenta has not yet been investigated.
literature
- PJ Hayward, JS Ryland: Handbook of the Marine Fauna of North-West Europe. Oxford University Press, Oxford 1995. Anseropoda placenta (Pennant), p. 667.
- Michel Glémarec, Monique Guillou (1996): Recruitment and year-class segregation in response to abiotic and biotic factors . Oceanologica Acta 19 (3-4), pp. 409-414.
- Monique Guillou, M. Diop (1988): Ecology and demography of a population of Anseropoda placenta (Echinodermata: Asteroidea) in the Bay of Brest, Brittany . Journal of the Marine Biological Association of the United Kingdom 68 (1), pp. 41-54. doi: 10.1017 / S0025315400050086
- Monique Guillou (1987): Étude du régime alimentaire d'Anseropoda placenta (Asteroidea: Echinodermata) en rade de Brest (Finistère, France) . Bulletin de la Société des sciences naturelles de l'Ouest de la France, supplément hors-série, pp. 133-140.
Web links
- SJ Rowley: Goose foot starfish (Anseropoda placenta) . H. Tyler-Walters, K. Hiscock (Eds.): MarLIN, The Marine Life Information Network. Marine Biological Association of the United Kingdom, Plymouth 2007.
- Bernard Picton: Anseropoda placenta - goosefoot starfish . Northern Ireland Priority Species. National Museums Northern Ireland, Cultra (Co. Down) 2006–2011.